FOS

A mighty mini-operating system!

Table of Contents

1. About The Project
   • The Team
2. Modules
   • System calls
   • Memory manager
   • Fault Handler
   • CPU Scheduler
3. Acknowledgments

About The Project

FOS is a basic, command-line based operating system.

This was a project for OS'23 course at FCIS, Ain Shams University.

• Supervisor and course lecturer: Dr. Ahmed Salah
• Mentor TA: Dr Rezq Mohammed

Team:

• Amna Ahmed - @thisisamna
• Khira Ebe - @monaya37
• Mariam Reda - @Mariam428
• Fatma Gamal - @FatmaGG
• Merna Tareq
• Manar Mansy - @manarmansyy

Built With

• C

Modules

System Calls

• System call implementation
• Linking user side and kernel side functions

Memory Manager

Managing user and kernel memory using two schemes

• Dynamic (block) allocator
  • Allocation using first fit and best fit strategies
  • Freeing allocated blocks
  • Reallocation using first fit strategy
• Page allocator
  • Allocating pages
  • Freeing memory pages
  • Lazy allocation/deallocation in the case of user memory

Fault Handler

Validate faulted addresses. If valid, handle the fault either through placement and replacement, using one of two schemes:

• FIFO (First in first out)
• LRU (Least recently used)

CPU Scheduler

• BSD scheduler implementation
• Environment (process) management
• Clock interrupt handler

Known issues

• Process command
• Sbrk (negative decrement) and sys_sbrk
• Freeing user memory

Acknowledgments

Thanks to Dr. Ahmed Salah, Dr. Rezq Mohamed and all TAs who supported this project.

Your help was invaluable to our team and every team. :)